• Bulletin of the Korean Chemical Society
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• v.31 no.1
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• pp.47-51
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• 2010

A powder, containing 80 percent of blue cobalt aluminate $(CoAl_2O_4)$ crystallites, was synthesized at $210 ^{\circ}C$ using a (metal nitrate-malonic acid-ammonium hydroxide-ammonium nitrate) system. The optimal amount of concentrated ammonia water and initial decomposition temperature were determined for the blue $CoAl_2O_4$ crystallites preparation. Three $CoAl_2O_4$ precursor pastes, corresponding to the various amounts of concentrated ammonia water, were prepared by evaporating the initial solutions in an electric furnace fixed at $80 ^{\circ}C$ under a vacuum of 25 torr. The initial solution was used to dissolve the starting materials. The powder with the maximum content (80%) of blue $CoAl_2O_4$ crystallites was prepared when the prepared precursor was decomposed at $210 ^{\circ}C$. The blue $CoAl_2O_4$ crystallite content in the prepared sample decreased with increasing initial decomposition temperature. For 0.2 mole of the $Al^{3+}$ ion, the chemical compositions of the precursor corresponded to molar ratios of 0.4, 1.40, 2.56 and 2.00 for the $Co^{2+}$ ion, malonic acid, ammonia and ammonium nitrate per mole of the $Al^{3+}$ ion, respectively. The blue $CoAl_2O_4$ crystallite content in the sample decreased with the amount of ammonia deviated from the optimal value. The characteristics of the powders were examined using X-ray diffraction, optical microscopy, Fourier transformation infrared spectroscopy and the Brunauer-Emmett-Teller technique.

• Journal of Environmental Policy
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• v.8 no.3
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• pp.81-113
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• 2009

This study conducted a regulatory impact analysis regarding the introduction of the Korean version of REACH(Registration, Evaluation and Authorization of Chemicals). The direct cost of the Korean REACH is estimated at a total of 101 billion Korean won over the 11 year period. The cost includes pre-registration, testing, registration, Chemical Safety Assessment(CSA) and Chemical Safety Report(CSR), evaluation, and the authorization costs of 15,223 chemical substances produced and imported more than 1 ton per year in Korea in 2006. With regard to the benefit, the only public health benefit is included in the estimation. Based on the available foreign and domestic data, this study estimated that the economic values of public health benefits are in the range of 33.2~138.6 billion Korean won if only the savings of the National Health Expenditures are considered and it reaches 203.9~1,640.3 billion Korean won if the willingness to pay(WTP) for disease prevention is included. This study proved that the Korean REACH passed the cost/benefit criteria. The benefit-cost ratio of the Korean REACH, however, is estimated to be lower than its EU counterpart. Thus it is suggested that a rigorous study to reduce the costs to industry be required before the Korean government introduces the Korean REACH.

• Journal of the Korean Chemical Society
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• v.48 no.3
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• pp.273-282
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• 2004

The synthetic technology of improved polyaluminiumchloride (IPAC) similar to characteristics of PACS was established with minimum expense for modifying existing production line. The conditions for activating silicate was studied before the synthesis of IPAC, and the IPAC was synthesised with raw materials such as aluminumhydroxide and concentrated hydrochloric acid, followed by adding activated silicate and alginate. The specification of product, chemical structure, and coagulating properties were tested by using specification testing method, instrumental analytical method, and Jar tester, respectively. As a result, the product, IPAC, contained aluminium oxide content more than 17%, and no precipitation was shown at all while the IPAC solution was preserved, and the larger floc and faster coagulation were represented compared to existing PAC under the same conditions. It was suggested that these synthetic technology could be applied to the existing production line for producing PAC without approximately cost raising factor because of adding sulfuric acid-activated silicate instead of sodium sulfate.

• Polymer(Korea)
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• v.29 no.5
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• pp.481-485
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• 2005

In this work, the thermal and mechanical properties of vapor grown carbon nanofibers (VGCNFs)-reinforced difunctional epoxy (EP) composites were investigated in the presence of the 0, 0.1, 0.5, 1.0, and $2wt\%$ VGCNFs. The thermal properties of the VGCNFs/EP composites were studied by thermo-mechanical analysis (TMA) and dynamic mechanical analysis (DMA). The mechanical properties of the VGCNFs/EP composites were also examined by universal testing machine (UTM), falling impact test, and the friction and wear tests. From experimental results, the thermal and mechanical properties of the VGCNFs/EP composites were improved with increasing the VGCNFs contents. This was due to the increase of crosslinking structure of the composites, resulting in improving the mechanical interlockings between VGCNFs and epoxy resins in the present composite system.

• Tribology and Lubricants
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• v.30 no.6
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• pp.343-349
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• 2014

Currently, in order to resist the scratching of the fuel rod surface while fabricating the fuel assembly of the light-water nuclear reactor, we use a solution of nitrocellulose, an explosive material, as a dry lubricant along with its solvent. However, the demand for developing safe and harmless aqueous alternative materials for environment-conservation and field-worker safety has increased. In this study, we demonstrate the preparation of a novel aqueous resin composite using a formulation of aqueous polymeric resin, alcoholic solvent, and water. Subsequently, we characterize this composite on the basis of hardness, adhesive property, and water solubility using plates similar to the fuel rod material. The insertion test of a fuel rod coated with the YS-3 composite shows load values of $18.8-20.5kg/cm^2$, which is comparable with $18.8-20.5kg/cm^2$ of the nitrocellulose coating agent. In addition, the depth and width of longitudinal scratches caused by the YS-3 composite test are 50% higher than those of the standard. We can develop a harmless and safe aqueous dry lubricant to replace the existing NC products through field testing of 264 pieces of fuel rods, after producing 350 kg of the YS-3 prototype. The scratch test for the rod surface showed that weight of chip of YS-3 prototype was smaller than that of NC before and after solvent treatment, indicating the properties of YS-3 prototype was comparable to the counterpart.

• Journal of Environmental Health Sciences
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• v.45 no.5
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• pp.457-464
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• 2019

Objectives: Quantitative structure-activity relationship (QSAR) is one of the effective alternatives to animal testing, but its credibility in terms of toxicity prediction has been questionable. Thus, this work aims to evaluate its predictive capacity and find ways of improving its credibility. Methods: Using $TOPKAT^{(R)}$, OECD toolbox, and $Derek^{(R)}$, all of which have been applied world-wide in the research, industrial, and regulatory fields, an analysis of prediction credibility markers including accuracy (A), sensitivity (S), specificity (SP), false negative (FN), and false positive (FP) was conducted. Results: The multi-application of QSARs elevated the precision credibility relative to individual applications of QSARs. Moreover, we found that the type of chemical structure affects the credibility of markers significantly. Conclusions: The credibility of individual QSAR is insufficient for both the prediction of chemical toxicity and regulation of hazardous chemicals. Thus, to increase the credibility, multi-QSAR application, and compensation of the prediction deviation by chemical structure are required.

• Journal of Environmental Health Sciences
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• v.47 no.5
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• pp.462-471
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• 2021

Background: The number of synthesized chemicals has rapidly increased over the past decade. For many chemicals, there is a lack of information on toxicity. With the current movement toward reducing animal testing, the use of toxicity big data and deep learning could be a promising tool to screen potential toxicants. Objectives: This study identified potential chemicals related to reproductive and estrogen receptor (ER)-mediated toxicities for 1135 cleaning products and 886 laundry products. Methods: We listed chemicals contained in cleaning and laundry products from a publicly available database. Then, chemicals that potentially exhibited reproductive and ER-mediated toxicities were identified using the European Union Classification, Labeling and Packaging classification and ToxCast database, respectively. For chemicals absent from the ToxCast database, ER activity was predicted using deep learning models. Results: Among the 783 listed chemicals, there were 53 with potential reproductive toxicity and 310 with potential ER-mediated toxicity. Among the 473 chemicals not tested with ToxCast assays, deep learning models indicated that 42 chemicals exhibited ER-mediated toxicity. A total of 13 chemicals were identified as causing reproductive toxicity by reacting with the ER. Conclusions: We demonstrated a screening method to identify potential chemicals related to reproductive and ER-mediated toxicities utilizing chemical toxicity big data and deep learning. Integrating toxicity data from in vivo, in vitro, and deep learning models may contribute to screening chemicals in consumer products.

• Journal of Trauma and Injury
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• v.37 no.3
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• pp.209-213
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• 2024

Purpose: Trauma patients are at an elevated risk of developing venous thromboembolism (VTE), with the subsequent mortality in patients requiring intensive care unit admission ranging from 25% to 38%. There remains significant variability in clinical practice related to VTE prophylaxis in trauma patients due to the frequent presence of contraindications impacting the timing and consistency of application. This study aimed to assess the effectiveness of the current practice of chemical VTE prophylaxis in trauma patients at a single Australian center. Methods: A prospective review was conducted on patients admitted to the ACT Trauma Service (Canberra, Australia) from July to November 2022. The included patients were 18 years or older, without a direct contraindication to anticoagulation, who received chemical VTE prophylaxis with low-molecular-weight heparin (enoxaparin) for at least three doses and underwent subsequent testing of anti-factor Xa (aFXa) levels. Results: During the study period, 187 patients were admitted, of whom 63 were included in the study. Of these, 47 patients achieved therapeutic levels of anticoagulation as determined by their aFXa levels, while 16 were subtherapeutic. The only statistically significant difference between the two groups was in weight, with patients in the subtherapeutic group weighing an average of 91.9 kg compared to 79.1 kg in the therapeutic group (P<0.05). Conclusions: A fixed-dose enoxaparin regimen was utilized, with limited individualization based on patient factors, such as injuries, comorbidities, and other biological factors. Sixteen patients (25%) had subtherapeutic VTE prophylaxis, as measured by aFXa levels. Higher weight was significantly correlated with inadequate VTE prophylaxis dosing. While age, sex, and smoking status might play important roles in clinical decision-making, weight-based dosing of low-molecular-weight heparin may be more effective in achieving adequate VTE prophylaxis.

• Membrane and Water Treatment
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• v.15 no.4
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• pp.163-176
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• 2024

Asymmetric flat sheet poly(vinylidene fluoride) (PVDF) membranes were fabricated using the phase inversion technique, employing four distinct solvents with varying solubility power: N, N-dimethylacetamide (DMAc), N, N-dimethylformamide (DMF), Dimethyl sulfoxide (DMSO), and N-Methyl-2-pyrrolidone (NMP). The influence of these solvents on the crystalline properties of the polymers was investigated using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) to elucidate their role in PVDF polymorphism during membrane formation. Our findings revealed significant variations in membrane crystalline phase due to the dissolution of PVDF in different solvents, with α-polymerization predominant in membranes cast with NMP and DMSO, while DMF and DMAc solvents favored β-type polymerization. Further, various additives including PEG-400, TiO2, LiCl, LiBr, acetone, ethanol, propanol, and water were employed to evaluate their impact on membrane morphology and properties. Scanning electron microscopy (SEM) and Ultimate testing machine (UTM) were utilized to analyze membrane morphology, while the tensile strength, contact angle, pore size, and porosity were estimated using the sessile drop method, imageJ, and gravimetric method, respectively. Our results demonstrated that all additives exerted influence on membrane morphology and properties depending on their characteristics and interactions with solvents and polymers. Notably, acetone, being volatile, facilitated the formation of a thin PVDF layer on the membrane surface, resulting in a reduced average pore size (0.18㎛). Conversely, LiCl and LiBr acted as pore-forming additives, yielding membranes with distinct pore characteristics and porosity. Moreover, water as a non-solvent additive induced pregelation during the nonsolvent-induced phase separation (NIPS) process, thereby promoting pore formation (53% porosity) and enhancing membrane hydrophobicity (104° contact angle). To evaluate the quality of synthesized membranes, permeate flux ranging from 16.2 L/m².hr to 27.9 L/m².hr with a salt rejection rate of 98 %, was evaluated using Vacuum Membrane Distillation (VMD).

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1109-1117
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• 2011

All objects emit infrared above absolute temperature 0K. Infrared thermography is one of the nondestructive testing technologies to measure the temperature of the object. Infrared thermography shows infrared image which in a longer wavelength than visible light. Infrared technology can be employed regardless of the type or state of the objects. Thus, infrared thermography technique has been used in a wide variety of manufacturing processes in areas such as mechanical, electrical, chemical and medical applications. The advancement of using infrared technology has been increasing. In this paper, the principle of lock-in infrared thermography and its applications were investigated, and the direction of future development was discussed.